The present invention relates generally to cathode ray tube (CRT) display devices, and more particularly to an apparatus and method for providing smooth scrolling in CRT display devices.
One of the display devices usable with digital transmission and display systems such as computers, is the CRT display device. These display devices are typically connected to a memory in which the data to be displayed are stored. The data are either stored wherein each picture element or pixel is represented by a bit, or wherein a coded representation is stored and then decoded prior to being displayed. The display is changed by changing in memory the data to be displayed, and then displaying the changed data. In these devices, the changes, including scrolling, are effected by digital means in the memory prior to display.
Patents of interest which disclose these and other similar apparatus are: U.S. Pat. No. 4,068,225 to Lee; U.S. Pat. No. 3,988,728 to Inoue et al; U.S. Pat. No. 4,019,090 to Wolff et al; U.S. Pat. No. 4,437,093 to Bradley; U.S. Pat. No. 3,787,833 to Rogers; U.S. Pat. No. 3,593,310 to Kievit; U.S. Pat. No. 3,706,075 to Fredrickson et al; U.S. Pat. No. 3,680,077 to Hoberecht; U.S. Pat. No. 4,196,430 to Denko; and U.S. Pat. No. 4,129,859 to Iwamura et al.
U.S. Pat. No. 4,301,393 to Shoji et al. discloses a Y-axis offset system for a cathode ray tube which uses a counter and a digital-to-analog converter to generate an offset voltage to automatically position a trace in a viewing area on the cathode ray tube face.